Huge financial losses occur regularly as a result of the counterfeiting of security sensitive documents. For example, credit card fraud resulting from the production of counterfeit credit cards and the fraudulent use of such cards to acquire goods is a huge cost to credit card companies. Such companies have taken steps such as the incorporation of holograms into credit cards to make the manufacture of counterfeits more difficult, but sophisticated criminals are able to duplicate such holograms, sometimes by infiltrating the card manufacturing facility. There remains therefore a need for reliable methods for authenticating security sensitive objects or documents such as credit cards.